1. FIELD OF THE INVENTION
This invention relates to a powdery oyster juice composition, a process for the production of the same, and a process for retaining the freshness of perishable foods for example fish, shellfish, livestock meats and vegetables, with the use of said powdery oyster juice composition.
2. DESCRIPTION OF THE PRIOR ART
A common means for retaining the freshness of perishable foods comprises refrigeration or cold storage thereof. In particular, refrigeration is an indispensable means for the prolonged storage of fishes, shellfishes and livestock meats. However there has been provided no effective means for avoiding or preventing the deterioration (for example, drying or oxidation) thereof during storage in a frozen state, though rapid chilling and glazing are effective therefor to some extent. Further, it is unavoidable in thawing frozen foods that the textures of fishes, shellfishes or livestock meats suffer from some changes. Namely, it is very difficult to restore these thawed foods to a state before refrigeration. When vegetables are frozen, the freezing of the moisture contained in their cells causes destruction of their textures, so that most of the frozen vegetables cannot be restored to a state before refrigeration. Therefore vegetables are usually cold-stored. In this case, however, they suffer from some troubles including drying during cold storage thereof.
When perishable foods such as fishes or shell-fishes (including prawns and crabs) which have not been heat-treated are rapidly chilled and then thawed, the textures of the foods are weakened as compared with those before chilling, even when they are neither dried nor oxidized. In the case of shucked prawns, for example, an unfrozen fresh prawn is bent just like a hook when hung bottom up. In contrast, a shucked prawn, when frozen and thawed, forms into a stick when hung in the same manner. When picked with fingers, the trunk of an unfrozen fresh prawn is tight and elastic, while the trunk of a frozen and thawed prawn is soft and less elastic. This difference in elasticity between the unfrozen and frozen prawns is clearly noticeable when they are taken uncooked, for example, as sashimi. When roasted directly on fire or on an iron plate, an unfrozen prawn undergoes little shrinkage and is juicy, while a frozen and thawed prawn undergoes serious shrinkage and is not juicy. The above-mentioned differences in elasticity, shrinkage upon roasting and juiciness between the unfrozen and frozen prawns are similarly observed in other fishes and shellfishes such as the adductor muscle of a scallop, and in livestock meats.